How Hummingbirds Got Their Sweet Tooth

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Hummingbirds are the only type of birds that are drawn to sweet flavors, according to a new study conducted by scientists from Harvard. The study was published in the journal Science and examined the genetic codes of ten different types of birds, reports Zee News.

Hummingbirds love sweet

According to scientists, hummingbirds developed their ability to detect sweetness through a savory taste reception that mostly focuses on amino acid flavors. Those who participated in the study said that only a change in one receptor can cause animals to change their behavior. Scientists believe that such changes can result in a species becoming more diversified.

To test this theory, scientists cloned the taste receptor genes from chickens, hummingbirds and swifts. It took three years to do it. They wanted to test and see what their genes’ proteins were responding to. Ten years ago, scientists initially published the chicken genome’s complete sequence, and it was discovered that the birds do not have a functioning sweet taste receptor, according to National Geographic.

Hummingbirds don’t respond to amino acids

The researchers found that the receptors in swifts and chickens responded strongly to amino acids, while hummingbirds’ receptors responded weakly. Instead of amino acids, they found that hummingbirds’ receptors only respond to carbohydrates, which are the sweet flavors.

After mixing together subunits of the hummingbird and chicken taste receptors, researchers found 19 different mutations, although they believe there could be more involved in the shift from the so-called “umami,” or amino acid flavors, to the carbohydrate flavors. They believe that the mutations could have made it possible for hummingbirds’ umami receptor to taste sweet.

Scientists say a lot of species have lost the use of their taste receptors but that it’s possible that the hummingbird is the first to actually change how it uses the receptor. They are now trying to determine if all hummingbird species have a repurposed umami taste receptor and whether they are the only type of bird that does. They’re testing other birds that eat nectar, like the honeyeater.

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